It is known a global-positioning-system-receiver (GPS-receiver) that indicates a receiver-coordinate of a host-vehicle has a receiver-error. That is there is expected to be some error associated with the receiver-coordinate indicated by the GPS-receiver on the host-vehicle, and economical examples of GPS-receivers that are used on many vehicles may have more error than preferred, especially in situations the GPS-receiver is the sole means of determining the location of the host-vehicle on a roadway.